| From: | "Drouvot, Bertrand" <bertranddrouvot(dot)pg(at)gmail(dot)com> |
|---|---|
| To: | Amit Kapila <amit(dot)kapila16(at)gmail(dot)com> |
| Cc: | Ajin Cherian <itsajin(at)gmail(dot)com>, shveta malik <shveta(dot)malik(at)gmail(dot)com>, Peter Smith <smithpb2250(at)gmail(dot)com>, "Hayato Kuroda (Fujitsu)" <kuroda(dot)hayato(at)fujitsu(dot)com>, Bharath Rupireddy <bharath(dot)rupireddyforpostgres(at)gmail(dot)com>, Peter Eisentraut <peter(dot)eisentraut(at)enterprisedb(dot)com>, Bruce Momjian <bruce(at)momjian(dot)us>, Ashutosh Sharma <ashu(dot)coek88(at)gmail(dot)com>, Andres Freund <andres(at)anarazel(dot)de>, pgsql-hackers <pgsql-hackers(at)postgresql(dot)org>, Alvaro Herrera <alvherre(at)alvh(dot)no-ip(dot)org> |
| Subject: | Re: Synchronizing slots from primary to standby |
| Date: | 2023-10-25 09:48:33 |
| Message-ID: | b099ebc2-68fd-4c08-87ce-65fc4cb24121@gmail.com |
| Views: | Raw Message | Whole Thread | Download mbox | Resend email |
| Thread: | |
| Lists: | pgsql-hackers |
Hi,
On 10/25/23 6:57 AM, Amit Kapila wrote:
> On Tue, Oct 24, 2023 at 3:35 PM Drouvot, Bertrand
> <bertranddrouvot(dot)pg(at)gmail(dot)com> wrote:
>>
>> On 10/24/23 7:44 AM, Ajin Cherian wrote:
>>> On Mon, Oct 23, 2023 at 11:22 PM Drouvot, Bertrand
>>> <bertranddrouvot(dot)pg(at)gmail(dot)com> wrote:
>>
>> 2) When we create a subscription, another slot is created during the subscription synchronization, namely
>> like "pg_16397_sync_16388_7293447291374081805" (coming from ReplicationSlotNameForTablesync()).
>>
>> This extra slot appears to have failover also set to true.
>>
>> So, If the standby refresh the list of slot to sync when the subscription is still synchronizing we'd see things like
>> on the standby:
>>
>> LOG: waiting for remote slot "mysub" LSN (0/C0034808) and catalog xmin (756) to pass local slot LSN (0/C0034840) and and catalog xmin (756)
>> LOG: wait over for remote slot "mysub" as its LSN (0/C00368B0) and catalog xmin (756) has now passed local slot LSN (0/C0034840) and catalog xmin (756)
>> LOG: waiting for remote slot "pg_16397_sync_16388_7293447291374081805" LSN (0/C0034808) and catalog xmin (756) to pass local slot LSN (0/C00368E8) and and catalog xmin (756)
>> WARNING: slot "pg_16397_sync_16388_7293447291374081805" disappeared from the primary, aborting slot creation
>>
>> I'm not sure this "pg_16397_sync_16388_7293447291374081805" should have failover set to true. If there is a failover
>> during the subscription creation, better to re-launch the subscription instead?
>>
>
> But note that the subscription doesn't wait for the completion of
> tablesync.
Right.
> So, how will we deal with that? Also, this situation is the
> same for non-tablesync slots as well. I have given another option in
> the email [1] which is to enable failover even for the main slot after
> all tables are in ready state, something similar to what we do for
> two_phase.
Oh right that looks like a better option (enable failover even for the main slot after
all tables are in ready state).
Regards,
--
Bertrand Drouvot
PostgreSQL Contributors Team
RDS Open Source Databases
Amazon Web Services: https://aws.amazon.com
| From | Date | Subject | |
|---|---|---|---|
| Next Message | tender wang | 2023-10-25 09:58:21 | Re: BUG #18167: cannot create partitioned tables when default_tablespace is set |
| Previous Message | Ashutosh Bapat | 2023-10-25 09:48:01 | Re: Use virtual tuple slot for Unique node |